1. Field of the Invention
The present invention relates to gas turbine engines and, more particularly, to a gas turbine engine capable of having compact dimensions, light weight, and improved fuel efficiency as well as providing operational stability.
2. Description of Related Art
Currently, a typical conventional gas turbine engine 9 generally comprises a compressor section 91, a combustor section 92, and a turbine section 93, wherein an engine core turbine rotor 95 having a shaft 950 is positioned inside a casing 94, as shown in FIG. 1. An annular space is thereby formed between the shaft 950 and the casing 94 which substantially encloses a conventional annular combustor 96 within.
Referring to FIG. 1, air is compressed after passing through compressor stator blades 941 and compressor rotor blades 981 to become highly pressurized gas due to centrifugal force and diffusion effect. Compressed air then enters the annular combustor 96 to be mixed with fuel for combustion which produces highly pressurized gas stream that is also high in temperature; the gas stream is then forced out through a plurality of engine core turbine rotor blades 951 which drive the shaft 950 and the compressor rotor blades 981 into rotation. Subsequently, the gas stream passes through a plurality of turbine rotor blades 971 which drives a turbine rotor 97 into rotation to produce shaft power.
Nevertheless, an extra annular space is required inside the casing 94 to accommodate the annular combustor 96 of the aforementioned conventional gas turbine engine 9 which not only makes compact engine designs difficult but also causes heat in the combustor to dissipate without performing any mechanical work.
After air is compressed as it enters the compressor section 91, it is fed directly into the annular combustor 96 to be combusted with fuel without any preheating. Due to the lack of preheating the air prior to combustion, extra fuel is needed inside the annular combustor 96, which decreases fuel efficiency of the conventional gas turbine engine 9.
Furthermore, as shown in FIG. 1, the compressor rotor blades are formed on a compressor rotor 98 positioned in the front of the gas turbine engine 9 while the engine core turbine rotor 95 and the turbine rotor 97 are positioned in the rear. Any uneven vibration transmitted through the axis of the shaft 950 can cause unstable engine operation; especially when high operating temperature within the turbine section 93 tends to shorten the operation life of different mechanical parts such as a bearing.
Therefore, it is desirable to provide an improved gas turbine engine capable of having improved operational stability while at the same time having the advantages of compact design, light weight, and enhanced fuel efficiency to mitigate and/or obviate the aforementioned problems.
A primary object of the present invention is to provide a gas turbine engine which employs a recuperator to improve on fuel consumption by using the recuperator as an energy-saving heat exchanger.
Another object of the present invention is to provide a gas turbine engine wherein a compressor rotor is concentrically positioned back-to-back with a turbine rotor on a single shaft to increase operational stability of the rotors.
Still another object of the present invention is to provide a gas turbine engine wherein a can-type combustor is used for alleviating heat-dissipation issues to improve efficiency of the combustion.
The present invention achieves the above-mentioned objects by providing a gas turbine engine comprising: a casing, a recuperator functioning as a heat exchanger, a combustor, and a turbine engine rotor comprising a coaxial compressor rotor and a turbine rotor; wherein, the casing has an approximately cylindrical shape having a circular shoulder portion which extrudes outwardly and forms a casing opening to a first end and a bottom plate sealing a second end of the casing on the opposite side. The recuperator functions as a heat exchanger and includes two spaced-apart divider walls which extend spirally inwards from an inner perimeter of the casing towards an inner chamber inside the casing. A combustor is installable within the chamber having a main exhaust opening formed towards the first opening and a plurality of air holes. Since the entire design of the combustor is approximately a can-type shape, the spatial requirement associated with the engine thus can be significantly reduced, and eliminates the heat-dissipation issues, greatly increases fuel efficiency during engine operation.
The heat exchanger further comprises a top plate spacing a gap with the shoulder portion of the casing, the two spaced-apart divider walls sealing both ends with the top plate and the bottom plate and forming spirally a compressed air passageway and a turbine exhaust gas passageway adjacent to each other throughout the heat exchanger. The compressed air passageway of the heat exchanger connects the inner chamber with the gap, and the turbine exhaust gas passageway connects the main exhaust opening of the combustor with an exhaust vent formed on the bottom plate. Because the compressed air passageway and the turbine exhaust gas passageway are spirally formed adjacent to each other, air coming through the compressed air passageway is preheated along the way by the exhaust gas vented through the turbine exhaust gas passageway. Thus, the improved fuel efficiency of a gas turbine engine according to the present invention is achieved simply by combusting less fuel with higher-temperature compressed air.
Another aforementioned object of the present invention is to improve on the operational stability of a gas turbine engine by having the compressor rotor and the turbine rotor formed back-to-back on a single shaft concentrically; wherein, compressor rotor blades are perimetrically formed onto the compressor rotor directly behind the main exhaust opening. Thus, the operational stability of the gas turbine engine according to the present invention is improved by having a significantly shorter shaft than that of a conventional gas turbine engine. Another advantage of having a back-to-back rotor arrangement is that the operation life of the shaft bearing is prolonged because it is positioned farther away from the combustor than that of a conventional gas turbine engine.
Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.